Gatwick airport to Southampton

I think you will find train and bus each have different advantages. Train will be a little bit faster but involves changing trains with your luggage. Bus will take a little longer, bus luggage gets put under bus by driver and you don’t deal with it until destination.

I have stayed at Premier Inn West Quay in Southampton. I would not characterize it as a 4-5 star hotel. It was clean, had air conditioning, had elevator, and was clearly catering to the cruise crowd with a dedicated taxi phone line, etc. In house restaurant or many restaurants available in mall across the street. Some interesting wall ruins nearby. There is also a Holiday Inn Express nearby. Cab to Mayflower dock less than £10.

Gatwick to Southampton [SOU] on the National Express bus you have to go via Heathrow, where you change bus, at Terminal 5.

By train the former direct trains have ceased running. There is an hourly train at 39 minutes past each hour (destination Bognor Regis), change at Barnham, or the fastest route is at 32 minutes past each hour, going the wrong way- to Clapham Junction where you change onto a fast train to SOU. In this case I would rather be the tortoise than the hare, and change at Barnham than the busy and very large Clapham Junction.

No need to buy in Advance on either bus or train. The via Barnham train route you just turn up and buy an Off Peak Day Single for £21.10, half the price of the bus. Via Clapham Junction is a lot more expensive.

I know and appreciate where Carol is coming from, if it was from Heathrow then National Express would be the clear favourite, in this case to me the train via Barnham is the obvious and simple solution.